Program Information
Evaluation of the Variation in Internal Target Volume of a Moving Lung Tumour Using Four Dimensional Computed Tomography
ARUN BALAKRISHNAN1*, s prasath2 , R SHRIMALI3 , I MALLICK4 , S CHATTERJEE5 , RAMESH BABU6 , (1) TATA MEDICAL CENTER, Kolkata, WEST BENGAL, (2) ,,,(3) TATA MEDICAL CENTER, Kolkata, WEST BENGAL, (4) TATA MEDICAL CENTER, Kolkata, WEST BENGAL, (5) TATA MEDICAL CENTER, Kolkata, WEST BENGAL, (6) VIT UNIVERSITY, Vellore, TAMIL NADU
Presentations
SU-I-GPD-J-22 (Sunday, July 30, 2017) 3:00 PM - 6:00 PM Room: Exhibit Hall
Purpose: To evaluate the variation in internal target volume of a moving lung tumour due to inconsistency in free breathing rate in the patients in lung SBRT (Stereotactic Body Radiation Therapy) using retrospective Four Dimensional Computed Tomography. Also analysis of phase error after binning in the moving phantom.
Methods: The programmable motion Quasar phantom with 6mm longitudinal displacement of lung equivalent cedar cylinder insert containing off-set placed 2.5 cm diameter tumour density sphere as tumour and sine wave rotational mode with 1cm amplitude platform with 6 dot marker and 4 seconds was set for seconds per breath (SPB). In CT machine, 1/10th of the breathing period read from RPM (Real-time Position Management) console feed into cine time between images. Cine duration was set 1second added breathing period and inter-scan time was set 1 second. The images were sorted into 10 phases based on the temporal correlation between surface motion and data acquisition with an Advantage Workstation. The results of GE Advantage 4D, Binned 10 phase images, MIP and AIP (Average Intensity Projection) were imported in Varian Eclipse version 10.0. From MIP set, the ITV (tumour sphere created elliptical volume) structure created under -400 HU window width to estimate the volume in CC. The same procedure was repeated with known error value of ±0.5 second in cine time between images. The whole procedure were repeated five times for consistency.
Results: The observed Internal Target Volume (ITV) volume variations was ≤-1.9 % error observed and <2 % maximum phase error than the actual 4DCT breathing period setting in 10 bins 4DCT image protocol.
Conclusion: There is no significant error due to small averaging variation in breath period entered cine time between images during 4DCT imaging.
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